Dishwasher wherein liquid is circulated with granules and separation device for separating granules from the liquid

ABSTRACT

A dishwasher for washing with granules heavier than liquid, comprises a washing chamber (1), a device (7) for spraying washing liquid with or without granules against dishes in the washing chamber, a tank (10) which is connected to an outlet (11) from the washing chamber, and a circulation pump (5), the suction side of which is joined to an outlet (4) from the tank, and the pressure side of which is joined to a manifold (6) for conducting liquid sucked in from the tank, with or without granules, to the spray device (7). According to the invention, the dishwasher comprises a dividing wall (8), defining an upwardly open tank chamber (12) in the tank. The upper edge of the wall is disposed beneath the upper limit of the tank. Furthermore, the outlet opening (11) of the washing chamber is disposed above the tank chamber (12) defined by the dividing wall.

FIELD OF THE INVENTION

The present invention relates to a heavy-duty dishwasher for washingwith granules heavier than liquid, comprising a washing chamber, a spraydevice for spraying washing liquid, with or without granules, againstarticles to be washed in the washing chamber, a tank which is Joined toan outlet from the washing chamber, and a circulation pump, the suctionside of which is joined to an outlet from the tank and the pressure sideof which is Joined to means for conducting liquid sucked into the tank,with or without granules, to the spray device.

A number of heavy-duty dishwashers are previously known in which blastparticles or granules together with the washing liquid are thrown orsprayed against the articles to be washed.

BACKGROUND OF THE INVENTION

EP-A1-0 016 895 reveals a heavy-duty dishwasher of this type, whichcontains in its tank a granule collecting sieve container with its inletconnected to the washing chamber and its outlet connected to the suctionchamber of the pump. A gate closes in one end position the outlet of thesieve container and thereby opens a connection between the suctionchamber and portions of the tank lying outside the sieve container, sothat only liquid is sucked up by the pump: In the other end position ofthe gate, said connection is closed and the pump sucks liquid from thetank via the sieve container, whereby the liquid sucked in has granulesfrom the sieve container. In addition to the fact that such a dishwasherhas relatively complicated construction, it requires time consumingmaintenance in order to prevent the sieve container from being cloggedby food particles carried by the circulating liquid.

EP-A2-0 195 959 and EP-A1-0 169 847 show dishwashers of theabove-mentioned type for granules heavier than the washing liquid. Insuch machines, a vertically moveable cylinder is disposed at the bottomoutlet of the tank. In the upper position of the cylinder, liquid andgranules flow from the tank through the annular gap between the lowerend of the cylinder and the bottom outlet of the tank. This gap isclosed when the cylinder is in its lower position, where liquid from thetank is sucked in through a gap between the upper end of the cylinderand a conical plate which prevents granules from flowing from above intothe upper open end of the cylinder. The dishwasher according to EP-A2-0195 959 also contains an annular sieve plate in the last mentioned gapin order to prevent granules from accompanying liquid sucked into theupper end of the cylinder. In EP-A1-0 169 847, it is assumed that thegranules will sink by their own weight to the bottom of the tank, andthat only liquid will be sucked into the upper end of the cylinder whenthe cylinder assumes its lower end position. However, granules whichpass by the upper end of the cylinder when it serves as a pump inletwill be sucked into the inlet, and therefore it takes a relatively longtime for such a machine to assume a state where only liquid iscirculated and all the granules have sunk to the bottom of the tank.

SUMMARY OF THE INVENTION

The present invention is intended to achieve a heavy-duty dishwasherusing granules, said dishwasher not containing any sieve element toprevent granules from accompanying liquid sucked into the pump; andwhich can be immediately switched from a state where liquid withgranules is sucked up by the pump to a state where only liquid is suckedinto the pump, and which also has a simple and sturdy design with fewcomponents.

For this purpose, a heavy-duty dishwasher of the type described by wayof introduction is characterized in that it comprises a dividing wall,defining an upwardly open chamber in the tank, the upper edge of saidwall being disposed beneath the upper limit of the tank and that theoutlet opening of the washing chamber is disposed above the chamberdefined by the dividing wall. In this dishwasher, the upper edge of thedividing walls serves as a spillway and it allows liquid supplied to thechamber defined in the tank to overflow to the portion of the tank lyingoutside said chamber, while granules will sink due to gravity to thebottom of the chamber. Due to the fact that the overflow from thischamber to the portion of the tank lying outside the chamber occursessentially at the surface of the liquid held in the chamber, thegranules sinking in the chamber will only be given a small horizontalcomponent of movement due to surface flow, and this means that all ofthe granules falling down from the washing chamber will sink to thebottom of the tank chamber.

In a preferred embodiment of the invention, the dividing wall at itslower end comprises a portion which can be pivoted between the firstposition in which the tank chamber defined by the wall is closed at itslower end, and a second position in which the lover portion of the tankchamber is in communication with the rest of the tank. Furthermore, thelower portion of the tank is preferably tapered to a bottom outlet andthe lower end of the dividing wall is disposed to one side of and abovethe bottom outlet of the tank. By this design, the dishwasher can easilyswitch between washing with and without granules in the circulatingwashing liquid, at the same time as the positioning of the dividing wallaway from the bottom outlet means that the flow about the bottom outletwill not, or only minimally, be effected by the operation of thepivoting portion of the dividing wall.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to theaccompanying drawings, in which

FIG. 1 shows schematically a cross-sectional view of a preferredembodiment of a heavy-duty dishwasher according to the invention whilewashing solely with washing liquid,

FIG. 2 shows a similar cross-section of the dishwasher in FIG. 1 whilewashing with granules in the washing liquid, and

FIGS. 3-5 each show schematically a cross-sectional view of the tank inFIG. 1 with different variations of a dividing wall arranged therein.

The heavy-duty dishwasher shown in FIGS. 1 and 2 comprises a washingchamber 1, in which the dishes to be washed can be placed in a suitablymanner and held in place. An outlet from the washing chamber is definedby two bottom plates 2 and 3. In the present case, the washing chamberis rectangular and the bottom plates extend between the walls of thetank leaving a rectangular outlet opening 11. The bottom plates 2, 3 arealso somewhat inclined in order to make sure that liquid and granulesfalling thereon will be led to the outlet opening 11.

Beneath the washing chamber there is a tank 10 with a bottom outlet 4.Preferably, the tank tapers at its bottom towards the bottom outlet.

The dishwasher also comprises a circulation pump 5, which is connectionon its suction side to the bottom outlet 4 of the tank. The pressureside of the pump 5 is Joined to manifolds 6, of which only one is shownin the figures, from which manifolds the nozzles 7 extend. In order tounderstand the present invention, it is sufficient to know that thenozzles are arranged to direct and spray liquid sucked up by the pumpagainst the dishes in the washing chamber, and therefore the descriptionwill not deal in detail with the arrangement of the pipes and nozzles.

The tank 10 has a dividing wall 8 which defines an upwardly open tankchamber 12. The outlet opening 11 from the washing chamber is locatedabove the tank chamber 12. The dividing wall 8 extends parallel to thelongitudinal sides of the rectangular outlet opening 11, i.e.perpendicular to the cross-sectional plane of the figures, and islaterally spaced from said opening.

At its lower portion, the dividing wall 8 has a pivoting portion, whichin the embodiment shown consists of a gate 9 pivotable above a centralaxis. This gate can extend between the tank walls and thus constitutethe entire lower portion of the dividing wall or can be an integratedportion of the lower portion of the dividing wall and be hinged thereto.The gate 9 can also be hinged about its upper or lower end, but theembodiment shown in FIGS. 1 and 2 is preferable since the gate 9 can berotated between its closed and open positions by always rotating thegate in the same direction. In other words, no reversable pivotmechanism is required. The pivot mechanism for the gate 9 is of suitabletype and is designed so that the gate will either assume the positionshown in FIG. 1, in which the lower end of the tank chamber 12 is closedby the gate, or the position shown in FIG. 2, in which the lower end ofthe chamber 12 is open and connects the tank chamber 12 to the rest ofthe tank. Suitably, actuation of the pivot mechanism for the gateresults in the gate being turned a quarter revolution, for example withthe aid of a stepping motor.

The function of the heavy-duty dishwasher shown is quite simple. Thepump 5 sucks liquid from the lower portion of the tank 10 and the liquidsucked in is sprayed through the nozzles 7 against the dishes in thewashing chamber. The liquid then falls down to the bottom of the washingchamber and flows through the outlet opening 11 down into the chamber 12of the tank 10. If the lower end of the tank chamber is closed and ifthe liquid level in the tank chamber lies below the upper edge of thedividing wall 8, this chamber will be filled to the upper edge of thewall and then overflow over said edge and into the rest of the tank 10.This circulation pattern is shown in FIG. 1.

FIG. 2 shows the circulation pattern when the lower end of the tankchamber 12 is open, i.e. when the gate 9 has been turned a quarter turnrelative to the position shown in FIG. 1. Due to the fact that the tankchamber now communicates with the rest of the tank, the liquid levels inthe tank chamber 12 and the rest of the tank will be evened out, andthis means that a liquid flow corresponding to the liquid flow suppliedto the tank chamber 12 via the outlet opening 11 will flow through theopen lower end of the dividing wall 8 into the rest of the tank 10.Thus, essentially only the liquid in the tank chamber 12 and in thelower portion of the tank 10 will participate in the liquid circulationshown in FIG. 2.

In FIGS. 1 and 2, the round rings symbolize the blast particles orgranules which are mixed into the washing liquid and which are heavierthan said liquid, for example plastic granulate. In normal washing inthe dishwasher shown, the granules are mixed into the liquid sucked inby the pump 5 and sprayed together with the liquid against the dishes sothat the blasting effect will knock off burned-on or dried-on foodresidue from the dishes. The heavy-duty dishwasher is then in theabove-described mode shown in FIG. 2.

After finished washing with the granules, the dishes must be rinsed withliquid alone in order to wash off the granules which may have stuck tothe dishes or to the walls of the washing chamber. To do this it issufficient to close the lower end of the tank chamber 12 by turning thegate 9 a quarter turn from the position shown in FIG. 2. The granulesmixed with the liquid at the lower portion of the tank will accompanythe liquid sucked into the pump, while the granules, which are mixedwith the liquid in the chamber 12, will sink by gravity to the bottom ofsaid chamber. By closing the tank chamber 12, initially no liquid willbe supplied to the portion of the tank outside the tank chamber 12, andthe liquid level there will drop until the tank chamber 12 is filled.Thereafter, there will be a flow as large as the flow sucked through thebottom outlet of the tank, which will flow over the upper edge of thedividing wall 8.

By dimensioning the dividing wall and placing it in such a manner thatthe volume of the tank chamber 12, which in the circulation mode shownin FIG. 2 extends above the liquid surface in the tank chamber and mustthus be filled before liquid overflows the upper portion of the dividingwall, is at least as great as the sum of the volume of the lower portionof the tank outside the tank chamber, containing liquid mixed withgranules, and the volume of the pipe system between the tank and thewashing chamber, it is possible to assure that all of the granules havebeen returned to the tank chamber 12 before the liquid begins tooverflow the upper edge of the dividing wall.

For such an arrangement it is, however, not necessary to assure thatgranules accompanying the liquid flowing out from the outlet opening 11are not drawn with liquid overflowing the upper edge of the dividingwall. Due to their kinetic energy, the granules will quickly passthrough a surface layer of the liquid in which the lateral flow takesplace without being imparted in any appreciable horizontal component ofmovement and then sink by gravity to the bottom of the chamber 12 wherethey are collected as shown in FIG. 1. Near the upper edge of thedividing wall 8, the lateral flow is however sufficiently strong to pullgranules with it, and therefore the dividing wall should be laterallyspaced from the outlet opening 11.

It is evident from the above that the heavy-duty dishwasher describedhere can be operated with a higher level of filling than that shown inFIGS. 1 and 2, in other words with a liquid level lying above the upperedge of the dividing wall 8. With such a level of filling, when washingwith liquid without granules, only surface flow will arise in the liquidsurface and the stronger flow in the vicinity of the upper edge of thedividing wall is eliminated. When washing with liquid containinggranules there arises, in addition to flow through the open lower end ofthe dividing wall as was described previously with refence to FIG. 2, asurface flow as well. For reasons mentioned previously, this surfaceflow will not appreciably effect the movement of the granules.

In order to give the granules sufficient kinetic energy to achieve therequired blast effect when the granules are sprayed against the dishes,the pump 5 must have large capacity, and this means that the suction inthe bottom outlet 4 of the tank 10 must be quite powerful. This createsa powerful turbulent flow in the vicinity of the bottom outlet. Thisturbulent flow means that the granules, which when the gate 9 is turnedfrom the closed to the open position, flow in high concentration out ofthe lower end of the tank chamber, will very quickly be distributed moreor less evenly in the liquid above the bottom outlet, and the steadystate shown in FIG. 2 when washing with granules, in which the granulesare relatively evenly distributed in the circulating liquid, will beachieved shortly after the gate is opened. As can be seen in FIGS. 1 and2, the volume of the tank chamber 12 is less than the volume of the restof the tank 10. This means that the liquid flow between the tank chamber12 and the rest of the tank which occurs to replace the liquid sucked upby the pump will be sufficiently strong to provide the granules with thesignificant horizontal component of movement, and this also contributesto achieving an even granular distribution relatively quickly.

FIGS. 3-5 show variants of the dividing wall 8. FIG. 3 shows a dividingwall 8₁ which can be pivoted between a vertical position and a positionin which the lower edge of the dividing wall is in contact with the tankwall and closes off a chamber 12 in the tank. The pivotability of thedividing wall 8₁ is indicated by an arrow in FIG. 3. This variantfunctions in principle in the same manner as the embodiment according toFIGS. 1 and 2.

FIG. 4 shows a dividing wall 8₂ which is pivotable between a lowerposition in which it closes off a tank chamber 12 and an upper positionin which it is in contact with one edge of the outlet opening 11.Functionally this variant differs from that in FIGS. 1 and 2 by virtueof the fact that when washing with granules, the granules are suppliedfrom above to the portion of the tank 10 containing the bottom outlet,and that the granules are imparted a horizontal component of movement byrolling down an inclined plane instead of being acted on by a liquidflow.

In FIG. 5, a dividing wall 8₃ is shown, comprising a bottom portion 9₃which is vertically moveable between a lower and an upper position.Functionally, this variant functions in principle in the same manner asthat shown in FIG. 4.

In a variant not shown, the entire dividing wall or a lower portionthereof is vertically moveable to open the lower portion of the chamberin the tank which said wall defines. This variant functions in the samemanner as the embodiment according to FIGS. 1 and 2.

By making the washing chamber with bottom plates which define an outletopening, it is possible to empty the dishwasher of granules in anelegant manner prior to cleaning thereof by placing a straining clothsack in the outlet opening.

The dishwasher embodiments described can of course be modified in anumber of ways within the scope of the invention. For example, thewashing chamber and the tank can have other cross-sectional shapes thanthose described and shown, and the outlet of the tank could be arrangedin a lateral wall of the tank. Furthermore, the outlet opening need notextend between the walls of the washing chamber but can be completelydefined by the bottom plates and also be non-rectangular, which permitsa corresponding modification of the horizontal cross-section of the tankchamber defining dividing wall. The invention will therefore only belimited by the scope of the attached patent claims.

I claim:
 1. Heavy-duty dishwasher for washing with granules heavier thanliquid, comprising a washing chamber, a spray device for sprayingwashing liquid against articles to be washed in the washing chamber, atank which is joined to an outlet opening from the washing chamber, acirculation pump having a suction side joined to a bottom outlet fromthe tank and a pressure side joined to means for conducting liquidsucked in from the tank to the spray device, and a dividing walldefining an upwardly open tank chamber for storing granules heavier thanliquid in the tank, said dividing wall having an upper end disposedbeneath the upper limit of the tank, and the outlet opening of thewashing chamber being disposed above the tank chamber defined by thedividing wall, said dividing wall at its lower end comprising a portionpivotable between a first position in which the tank chamber defined bythe wall is closed at its lower end, and a second position in which thelower portion of the tank chamber is in communication with the rest ofthe tank, said lower portion of the tank being tapered to the bottomoutlet, and said lower end of the dividing wall being located spacedlaterally from and higher than the bottom outlet.
 2. Dishwasheraccording to claim 1, wherein the outlet opening of the washing chamberis horizontally spaced from the upper end of the dividing wall. 3.Dishwasher according to claim 1, wherein the pivotable portion of thedividing wall is a gate.
 4. Dishwasher according to claim 3, wherein thegate is rotatable about a central axis.
 5. Dishwasher according to claim1, wherein the dividing wall is pivotable about its upper end. 6.Dishwasher according to claim 5, wherein the dividing wall is pivotablebetween a first position in which it is in contact with one edge of theoutlet opening of the washing chamber, and a second position, in whichit is in contact with the tank wall and delimits a chamber in the tank.7. Dishwasher according to claim 1, wherein the dividing wall comprisesa vertically movable portion, which is movable between a first positionin which it is in contact with the tank wall to delimit a chamber, and asecond position in which it is in contact with one edge of the outletopening of the washing chamber.
 8. Dishwasher according to claim 1,wherein the dividing wall is vertically movable in its entirety. 9.Dishwasher according to claim 1, wherein a lower portion of the dividingwall is vertically movable.